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Interface using resistors
Programming Header
MISO
MOSI
SCK
PB1
PE1
PE0
RST
SCK-PB1
PDO-PE1
PDI-PE0
Reset
AVR
Typical resistor values would be 1K. This circuit is fine if ports PB7, PE0 and PE1 are used as
inputs in your circuit and no communications are required. If Outputs are needed or RS2232
connections, especially higher than a few milliamps, then the multiplexed circuit is preferable.
Using an analogue multiplexer IC
PB1
PE1
PE0
Reset
AVR
AXY
BXY
CXY
A
B
C
INH
AX
BX
CX
AY
BY
CY
74HC4053
SCK
MISO
MOSI
PB1
PE1
PE0
RST
0V
To ISP
Connector
To User
Circuit
User
Circuit
MISO is called PDO and
MOSI is PDI on Mega devices
- Port E bits 0 and 1 NOT pins
on Port B.
